The present invention relates to a magnetic head and a method of producing the same. Particularly, it relates to a thin film magnetic head characterized by having an insulation layer made of a silicone-containing polyimide resin.
It has been proposed in Japanese Patent Laid-Open Nos. 135713/1977 and 90834/1981 that a condensation or addition polymerization type polyimide is applied to an insulation layer of a magnetic head.
However, an addition polymerization type polyimide exhibits a poor solubility in a solvent. Therefore, it is difficult to obtain a homogeneous or relatively thick coating film from a solution thereof, thus being unpractical.
On the other hand, a condensation polymerization type polyimide is free from the above disadvantage, but generates a low molecular compound such as water by the condensation at curing time to cause film defects such as blister of an insulation layer, frequently resulting in inferiority of the thin film magnetic head to which such a polyimide is applied, for example, disconnection, burnout or short-circuiting. Further, a condensation polymerization type polyimide is difficultly melted at the time of curing and heating, so that the surface of the polyimide film has unevenness. Accordingly, the magnetic film which is formed on the polyimide film has also unevenness, so that no high permeability could be attained (Japanese Patent Laid-Open Nos. 90834/1981 and 135713/1977).
Further, any polyimide has a poor adhesiveness, so that a magnetic head having an insulation layer made of such a polyimide has problems in reliability.